1. Field of the Invention
The present invention relates to combination locks. More precisely, the present invention relates to an electronic push button lock, having a pawl and solenoid locking mechanism to prevent lock handle rotation from the open or closed condition in the absence of a correct combination code being entered by a user.
2. Prior Art and Related Information
Electronic locks have gained wide popularity for several reasons. First, it is usually less expensive to fabricate the electronics necessary to decipher an open combination than it is to machine and assemble mechanical parts to perform the same finction. Second, the material and labor costs involved in manufacturing an electronic lock tend to be lower as compared to a completely mechanical combination lock.
Third, an electronic lock is sometimes superior to a mechanical lock in defeating a potential safe cracker. For example, it is sometimes possible to manipulate a mechanical combination lock by relying on sounds generated by the moving tumblers inside, thereby obtaining the correct combination through sounds. On the other hand, an electronic lock deciphers the dial-in combination without moving parts and therefore does not serve as a feedback mechanism to assist the safecracker in breaching the lock.
Fourth, electronic locks are popular in that they can be easily reprogrammed to change the combination when necessary. The reprogramming is easy to accomplish electronically perhaps with only a few keypunches. In contrast, a mechanical door lock requires disassembly of certain portions of the lock cylinder. In a hotel room setting, an electronic lock that is easily reprogrammed is significantly more advantageous than a key lock, for instance, because the former can be reprogrammed if the key to the lock is lost or stolen.
There are many variations of electronic locks in the art. For example, U.S. Pat. No. 4,665,727 to Uyeda discloses an electronic digital safe lock including a slide plate pivotally connected by an articulated linkage to a bolt operating lever for retracting the safe door locking bolts after digital input of the electronic lock combination. The invention of Uyeda further includes a mechanical bypass system wherein a manual combination lock can be manipulated to release the locked bolt.
U.S. Pat. No. 4,745,784 to Gartner discloses an electronic dial combination lock having a spindle journalled within the lock for movement within two degrees of freedom; i.e., rotational and axial displacement to cause engagement of a push pin located on an internal cam wheel to engage one of a plurality of pressure-sensitive switches within the lock. Each switch is capable of making a discrete electrical connection. Circuitry is included to detect when a predetermined, sequential order corresponding to the lock's combination is input through the pressure-sensitive switches. Gartner replaces conventional combination locks which typically comprise a plurality of tumbler wheels coaxially journalled on a rotating spindle which projects outwardly from the lock and is manipulated within one degree of freedom (rotational) through a predetermined, sequential series of rotations to operate a bolt within the lock.
U.S. Pat. No. 4,831,851 to Larson discloses a lock mechanism having a mechanical combination lock and an electronic lock, wherein the mechanical combination lock serves as a fail safe entry in case of failure of the electronic lock. In that same vein, U.S. Pat. No. 4,967,577 to Gartner et al. discloses an electronic lock with a manual combination override for opening of a lock by both an electronic and manual means.
A variation of an electronic door lock is provided in U.S. Pat. No. 4,899,562 to Gartner et al., wherein a single control knob is used for entering a predetermined combination through manipulation of the knob in a first arc of rotation, the code being entered by pushing the dial inwardly to bring a push pad into contact with individual switches in an array of electrical switches provided on a printed circuit board within the lock housing. The release of the door locking bolt is accomplished after entry of the predetermined code by further manipulation of the control knob through remaining portions of the knob rotations which were unavailable until after entry of the predetermined code. An alternative manner of entering the code for the electronic lock is provided through digital input pads located on the escutcheon.
In electronic locks, generally, the singular bolt or latch is mechanically operated. The electronic portion of the lock controls a solenoid which blocks or unblocks movement of the bolt thereby permitting the bolt to be respectively disabled or operated. Locks can have multiple bolt configurations, especially in a circular shape door for a safe. Typically, the bolts extend radially and are operated by a centrally located, rotating gear, cam, disk or the like. Examples of such multiple bolt locks include U.S. Pat. No. 4,127,995 to Miller, U.S. Pat. No. 4,342,207 to Holmes et al., and U.S. Pat. No. 4,493,199 to Uyeda.
An example of a solenoid-operated lock is U.S. Pat. No. 4,904,984 to Gartner et al. The patent teaches a combination lock with an additional security lock wherein an electrically operable solenoid, having an armature post normally biased outward of a solenoid body, is mounted to the combination lock housing so as to position the armature post normally to block movement of either the combination lock bolt or the bolt release lever associated with the bolt. An electrical signal generator is used to selectively operate the solenoid to retract the post from a bolt and/or bolt release lever blocking position to allow operation of the combination lock.
An electronic lock has its limitations. In a typical keypad code entry electronic lock, for example, it is often difficult by sight to determine if the locking bolt is in the retracted or extended position. Because the dial in prior art mechanical locks are often replaced by a digital keypad, there are no visual indications as to the locked or unlocked condition of the lock. Thus, someone who is distracted or absent-minded might easily leave the electronic lock in the open position; conversely, the electronic lock might be locked accidentally because the user was not aware of its locked condition based solely on any visual cues.
Therefore, a need presently exists for an electronic keypad operated combination lock wherein the keypad is merged into the handle. By virtue of the indicia on the keypad, it is possible to instantly recognize the open or closed condition of the lock based on the orientation of the indicia.